android开发 音乐，文件下载

今天和大家分享一下在android上怎么下载文件到手机上。

主要有两点大类容：

一，通过Http协议下载文件。

创建一个HttpURLConnection对象

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HttpURLConnection urlConn = (HttpURLConnection) url .openConnection();

HttpURLConnection urlConn = (HttpURLConnection) url
.openConnection();

获得一个InputStream对象

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inputStream = urlConn.getInputStream();

inputStream = urlConn.getInputStream();

访问网络的权限

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<uses-permission android:name="android.permission.INTERNET"/>

<uses-permission android:name="android.permission.INTERNET"/>

二，将下载的文件写入SDcard。

得到当前设备的SD卡目录

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Environment.getExternalStorageDirectory()

Environment.getExternalStorageDirectory()

设置访问SD卡的权限

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<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

下面给出具体的代码：

DownLoad.java

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import android.app.Activity;
import android.os.Bundle;
import android.util.HttpDownloader;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class DownLoad extends Activity {
private Button textButton;
private Button audioButton;

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
//文本下载
textButton = (Button) findViewById(R.id.textButton);
textButton.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View v) {
HttpDownloader http = new HttpDownloader();
//注意这里不要用localhost或者127.0.0.1，会报错的，因为android里是10.0.2.2

String txt = http
.download("http://10.0.2.2:8080/examples/123123.txt");
System.out.println(txt);
}
});
//音频下载
audioButton = (Button) findViewById(R.id.audioButton);
audioButton.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View v) {
HttpDownloader http = new HttpDownloader();
String result = http.download(
"http://10.0.2.2:8080/examples/123.mp3", "/music",
"zhou.mp3");
System.out.println(result);
}
});

}
}

import android.app.Activity;
import android.os.Bundle;
import android.util.HttpDownloader;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class DownLoad extends Activity {
private Button textButton;
private Button audioButton;

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
//文本下载
textButton = (Button) findViewById(R.id.textButton);
textButton.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View v) {
HttpDownloader http = new HttpDownloader();
//注意这里不要用localhost或者127.0.0.1，会报错的，因为android里是10.0.2.2
String txt = http
.download("http://10.0.2.2:8080/examples/123123.txt");
System.out.println(txt);
}
});
//音频下载
audioButton = (Button) findViewById(R.id.audioButton);
audioButton.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View v) {
HttpDownloader http = new HttpDownloader();
String result = http.download(
"http://10.0.2.2:8080/examples/123.mp3", "/music",
"zhou.mp3");
System.out.println(result);
}
});

}
}

FileUtil.java

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import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import android.os.Environment;

public class FileUtil {
private String SDCARDPATH;

public String getSDCARDPATH() {
return SDCARDPATH;
}

public FileUtil() {
// 得到手机存储器目录---因为各个厂商的手机SDcard可能不一样，最好不要写死了

SDCARDPATH = Environment.getExternalStorageDirectory() + "/";
}

/**
* 在SDcard上创建文件
*
* @param fileName
* @return File
*/
public File creatSDFile(String fileName) {
File file = new File(SDCARDPATH + fileName);
return file;
}

/**
* 在SDcard上创建目录
*
* @param dirName
*/
public void createSDDir(String dirName) {
File file = new File(SDCARDPATH + dirName);
file.mkdir();
}

/**
* 判断文件是否存在
*
* @param fileName
* @return boolean
*/
public boolean isFileExist(String fileName) {
File file = new File(SDCARDPATH + fileName);
return file.exists();
}

/**
* @param path
* 存放目录
* @param fileName
* 文件名字
* @param input
* 数据来源
* @return
*/
public File writeToSDCard(String path, String fileName, InputStream input) {
File file = null;
OutputStream output = null;
try {
//创建路径
createSDDir(path);
//创建文件
file = creatSDFile(path + fileName);
output = new FileOutputStream(file);
//以4K为单位，每次写4k

byte buffer[] = new byte[4 * 1024];
while ((input.read(buffer)) != -1) {
output.write(buffer);
}
// 清除缓存
output.flush();
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
// 关闭流
output.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return file;
}
}

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import android.os.Environment;

public class FileUtil {
private String SDCARDPATH;

public String getSDCARDPATH() {
return SDCARDPATH;
}

public FileUtil() {
// 得到手机存储器目录---因为各个厂商的手机SDcard可能不一样，最好不要写死了
SDCARDPATH = Environment.getExternalStorageDirectory() + "/";
}

/**
* 在SDcard上创建文件
*
* @param fileName
* @return File
*/
public File creatSDFile(String fileName) {
File file = new File(SDCARDPATH + fileName);
return file;
}

/**
* 在SDcard上创建目录
*
* @param dirName
*/
public void createSDDir(String dirName) {
File file = new File(SDCARDPATH + dirName);
file.mkdir();
}

/**
* 判断文件是否存在
*
* @param fileName
* @return boolean
*/
public boolean isFileExist(String fileName) {
File file = new File(SDCARDPATH + fileName);
return file.exists();
}

/**
* @param path
*            存放目录
* @param fileName
*            文件名字
* @param input
*            数据来源
* @return
*/
public File writeToSDCard(String path, String fileName, InputStream input) {
File file = null;
OutputStream output = null;
try {
//创建路径
createSDDir(path);
//创建文件
file = creatSDFile(path + fileName);
output = new FileOutputStream(file);
//以4K为单位，每次写4k
byte buffer[] = new byte[4 * 1024];
while ((input.read(buffer)) != -1) {
output.write(buffer);
}
// 清除缓存
output.flush();
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
// 关闭流
output.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return file;
}
}

HttpDownloader.java

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import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

public class HttpDownloader {
private URL url = null;

/**
* 下载文本文件
*
* @param urlStr
* @return
*/
public String download(String urlStr) {
StringBuffer sb = new StringBuffer();
String line = null;
BufferedReader buffer = null;
try {
buffer = new BufferedReader(new InputStreamReader(
getInputStreamFromUrl(urlStr)));
//一行一行的读取
while ((line = buffer.readLine()) != null) {
sb.append(line);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
buffer.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return sb.toString();
}

/**
* @param urlStr
* 文件所在的网络地址
* @param path
* 存储的目录
* @param fileName
* 存放的文件名
* @return 状态
*/
public String download(String urlStr, String path, String fileName) {
InputStream inputStream = null;
try {
FileUtil fileUtils = new FileUtil();
//判断文件是否已存在

if (fileUtils.isFileExist(path + fileName)) {
return "fileExist";
} else {
inputStream = getInputStreamFromUrl(urlStr);
File resultFile = fileUtils.writeToSDCard(path, fileName,
inputStream);
//如果resultFile==null则下载失败

if (resultFile == null) {
return "downloadError";
}
}
} catch (Exception e) {
//如果异常了，也下载失败
e.printStackTrace();
return "downloadError";
} finally {
try {
//别忘了关闭流

inputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return "downloadOk";

}

/**
* 连接到网络（ 抽取的公共方法）
*
* @param urlStr
* 文件所在的网络地址
* @return InputStream
*/
public InputStream getInputStreamFromUrl(String urlStr) {
InputStream inputStream = null;
try {
// 创建一个URL对象

url = new URL(urlStr);
// 根据URL对象创建一个HttpURLConnection连接

HttpURLConnection urlConn = (HttpURLConnection) url .openConnection();
// IO流读取数据
inputStream = urlConn.getInputStream();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return inputStream;
}

}

import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

public class HttpDownloader {
private URL url = null;

/**
* 下载文本文件
*
* @param urlStr
* @return
*/
public String download(String urlStr) {
StringBuffer sb = new StringBuffer();
String line = null;
BufferedReader buffer = null;
try {
buffer = new BufferedReader(new InputStreamReader(
getInputStreamFromUrl(urlStr)));
//一行一行的读取
while ((line = buffer.readLine()) != null) {
sb.append(line);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
buffer.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return sb.toString();
}

/**
* @param urlStr
*            文件所在的网络地址
* @param path
*            存储的目录
* @param fileName
*            存放的文件名
* @return 状态
*/
public String download(String urlStr, String path, String fileName) {
InputStream inputStream = null;
try {
FileUtil fileUtils = new FileUtil();
//判断文件是否已存在
if (fileUtils.isFileExist(path + fileName)) {
return "fileExist";
} else {
inputStream = getInputStreamFromUrl(urlStr);
File resultFile = fileUtils.writeToSDCard(path, fileName,
inputStream);
//如果resultFile==null则下载失败
if (resultFile == null) {
return "downloadError";
}
}
} catch (Exception e) {
//如果异常了，也下载失败
e.printStackTrace();
return "downloadError";
} finally {
try {
//别忘了关闭流
inputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return "downloadOk";

}

/**
* 连接到网络（ 抽取的公共方法）
*
* @param urlStr
*            文件所在的网络地址
* @return InputStream
*/
public InputStream getInputStreamFromUrl(String urlStr) {
InputStream inputStream = null;
try {
// 创建一个URL对象
url = new URL(urlStr);
// 根据URL对象创建一个HttpURLConnection连接
HttpURLConnection urlConn = (HttpURLConnection) url
.openConnection();
// IO流读取数据
inputStream = urlConn.getInputStream();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return inputStream;
}

}

AndroidManifest.xml

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<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="android.apps"
android:versionCode="1"
android:versionName="1.0">

<application android:icon="@drawable/icon" android:label="@string/app_name">
<activity android:name=".DownLoad"
android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>

</application>
<!-- 连接到网络的权限 -->
<uses-permission android:name="android.permission.INTERNET"/><!-- 访问SDcard的权限 -->
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
</manifest>

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="android.apps"
android:versionCode="1"
android:versionName="1.0">

<application android:icon="@drawable/icon" android:label="@string/app_name">
<activity android:name=".DownLoad"
android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>

</application>
<!-- 连接到网络的权限 -->
<uses-permission android:name="android.permission.INTERNET"/><!-- 访问SDcard的权限 -->
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
</manifest>

希望对大家有帮助。